1. Field of the Invention
The present invention relates to a hermetic motor-driving type compressor, and in particular to a head cover structure of a hermetic motor-driving type compressor which is capable of preventing leakage of a refrigerant gas at a high-pressure side and a low-pressure side and precisely combining a suction muffler to a head cover with reduced production costs.
2. Description of the Prior Art
Generally, a compressor pressurizes a fluid such as air and a refrigerant gas, etc. A compressor includes a driving unit placed inside a closed container and generating a driving force and a compressing unit being transmitted the driving force from the driving unit, sucking and compressing a refrigerant gas. In the compressor, when a driving force is generated in the driving unit by being applied power, the driving force is transmitted to the compressing unit, the compressing unit sucks a gas, compresses and discharges it.
In addition, a head cover structure used for the conventional hermetic motor-driving type compressor is divided into a high-pressure side and a low-pressure side in which a working fluid flows by an enclosure wall, and a suction muffler is installed at the low-pressure side.
As depicted in FIG. 1, a general hermetic motor-driving type compressor includes a closed container 1 formed by combination of an upper container 1a and a lower container 1b, and a motor driving unit and a compressing unit are formed inside the closed container 1.
The driving unit includes a stator 3, a plurality of springs 2s fixedly combined between the stator 3 and the bottom surface of the closed container 1 and elastically supporting the stator 3, and a rotator 4 placed so as to have a certain distance from the stator 3.
In the meantime, the compressing unit includes a hollow crank shaft 5 inserted-combined to the center of the rotator 4, a frame 2 combined between the upper portion of the crank shaft 5 and the upper inner circumference of the rotator 4, a balance weight 5c combined to the end of the crank shaft 5, an eccentric pin 5b installed at the upper surface of the balance weight 5c, a connecting rod 8 combined to a piston 7 slide-inserted into a cylinder 6 formed at the upper surface of the frame 2 and converting a rotation motion of the crank shaft 5 into a linear motion of the piston 7, a valve assembly 9 combined so as to cover a certain surface of the cylinder 6, and a head cover 10 combined to the valve assembly 9.
In the meantime, a piece 5e is inserted into the lower portion of the hollow crank shaft 5 in order to suck up oil L from the lower surface of the closed container 1, the sucked oil L is scattered in all internal spaces of the compressor through an oil channel 5a connected from the upper portion of the piece 5e to the internal space of the eccentric pin 5b. 
And, the working fluid is supplied to a compressing chamber 6xe2x80x2 of the cylinder 6 through a certain side of the head cover 10, a certain side of a suction muffler 11 reducing noise in suction is combined to the head cover 10, and the other side of the suction muffler 11 is connected to a suction pipe 12 suctioning the working fluid and a discharge pipe 23 discharging the compressed working fluid.
Moreover, the suction muffler 11 is made of a plastic material.
Hereinafter, the head cover structure of the conventional hermetic motor-driving type compressor will be described with reference to accompanying FIG. 2.
As depicted in FIG. 2, by an enclosure wall 10p, the internal space of the head cover 10 is divided into a lower pressure part 10b sucking a low-pressure working fluid by being mounted the suction muffler 11 and a high-pressure part 10t discharging the working fluid compressed in the compressing chamber 6xe2x80x2.
And, a gasket 13 and a valve plate 14 of the valve assembly 9 are orderly combined between the head cover 10 and the cylinder 6. In addition, the gasket 13 prevents leakage of the working fluid between the head cover 10 and the valve plate 14, particularly it prevents the leakage of the working fluid between portions corresponded to the upper surface 10g of the enclosure wall lop and the valve plate 14.
Hereinafter, the operations of the conventional hermetic motor-driving type compressor and the head cover will be described.
In the conventional hermetic motor-driving type compressor, when power is applied, the rotator 4 rotates by the electromagnetic interaction between the rotator 4 and the stator 3, and the crank shaft 5 constructed so as to be one-bodied with the rotator 4 also rotates.
By the operation, the eccentric pin 5b formed to be offset from a center of rotation of the crank shaft 5 performs the rotation circle motion, the connecting rod 8 connected to the eccentric pin 5b works together, and the piston 7 performs a linear reciprocating motion.
By the linear reciprocating motion of the piston 7, the working fluid is compressed in the compressing chamber 6xe2x80x2 of the cylinder 6, the compressed working fluid is discharged from the compressing chamber 6xe2x80x2, passes the valve plate 14 and reaches the high pressure side 10t of the head cover 10. And, the working fluid that reached the high-pressure side passes an additional discharge path (not shown) and a discharge noise reducing structure (not shown) and is discharged outside through the discharge pipe 23.
In the meantime, a low-pressure working fluid passes the suction muffler 11 through the suction pipe 12, reaches the valve plate 14 and flow into the compressing chamber 6xe2x80x2 by the control of the valve plate 14.
However, the head cover structure of the hermetic motor-driving type compressor in accordance with the prior art has problems as follows.
The head cover 10 is injection-molded out of aluminum or is cast, when the head cover 10 is molded out of aluminum, production costs may be increased due to the cost of materials. When the head cover 10 is cast, because a precise additional process for creating a flat surface 10a of the head cover 10 is required, production costs may be increased.
In addition, in the injection molding of the head cover 10, a bend is generated at the flat surface 10a due to heat distortion caused by a non-uniform cooling. Accordingly, there is a gap between the head cover 10 and the valve plate 14, a leakage of the working fluid occurs by the pressure difference between the high-pressure side lot and the low-pressure side 10b of the head cover 10, causes a pumping efficiency problem and abnormal operation of the compressor.
And, when a leakage of the working fluid occurs at the head cover 10, because the suction muffler 11 made of plastic material melts under the influence of the high temperature-high-pressure working fluid transmitted from the high-pressure side 10t or the gasket 13 ruptures, problems could be caused for the compressor.
In the meantime, in the injection-molding or casting of the head cover 10, because a burr occurs at the external boundary surface, an interference occurs in the combination of the suction muffler 11 and the lower pressure side 10b of the head cover 10.
And, a height of the head cover 10 is different from a mounting height of the suction muffler 11, when the head cover 10 mounted with the suction muffler 11 is installed to the cylinder 6, a gap occurs between the head cover 10 and the suction muffler 11, accordingly a leakage of the working fluid may occur.
In order to solve the above-mentioned problems, the mold of the head cover has to be modified or has to be made anew, accordingly, an enormous expense loss may occur.
In order to solve the above-mentioned problems, it is an object of the present invention to provide a head cover structure for a hermetic motor-driving type compressor, which is capable of reducing the cost of materials.
It is another object of the present invention to provide a head cover structure of a hermetic motor-driving type compressor, which is capable of preventing leakage of a working fluid at a head cover.
It is still another object of the present invention to provide a head cover structure of a hermetic motor-driving type compressor which is capable of preventing interference due to a burr in installation of a suction muffler to a head cover and modifying easily a mounting height in installation of the head cover to a cylinder.
In order to achieve the above-mentioned objects, a head cover structure of a hermetic motor-driving type compressor in accordance with the present invention includes a front head cover 30 having a space divided into a low-pressure side 30b sucking a refrigerant by having installed a suction muffler 21 and a high-pressure side 30t discharging the refrigerant b) an enclosure wall 30p, and a rear head cover 40 combined to the rear surface of the front head cover 30 and having a space divided into a low-pressure side 40b and a high-pressure side 40t by an enclosure wall 40p.